Hints for HW#6

In the first part you should be able to show that the period of a
rotating white dwarf - always larger than the one that you calculate (!)
- is inconsistent with the observed (1/30) seconds period.

Same reasoning with b.

Just for comparison: If a satellite goes around the earth just above its atmosphere then according to the formula given in 90 minutes. (that's accurate). However, earth spins in 24 hour, which is a longer period. So neutron stars can have periods LONGER than the ~10^-6 seconds that you will find, but not less. Same for white dwarfs.